Custom Search Form on Django

I'm facing some issues on Django and for this searchform I am using Django, Ajax and HTML, I haven't found any error and there is no error displayed on the website. So I hope someone could show me my faults.

here is the codes:

models.py

class Article(models.Model):
    user = models.ForeignKey(User)
    titre = models.CharField(max_length=100, unique=True)
    contenu = RichTextField(null=True)

    def __str__(self):
        return self.titre

views.py

    def index(request):

    context = {'derniers_articles': Article.objects.all()}
    context.update(csrf(request))

    populateContext(request, context)
    return render_to_response('index.html', context)


    def search_titles(request):
        if request.method == "POST":
            search_text = request.POST['search_text']
        else:
            search_text = ''

        articles = Article.objects.filter(titre__contains=search_text)
        return render_to_response('ajax_search.html', {'articles':articles})

ajax_search.html

{% if articles.count > 0 %}

{% for article in articles %}
<li>{{ article.titre }}</li>
{% endfor %}

{% else %}

<p>Nothing to do here.</p>
{% endif %}

urls.py

url(r'^search/$', 'article.views.search_titles', name='search'),

index.html

{% csrf_token %}
<input type="text" id="search" name="search"/>

<ul id="search-results"></ul>

ajax.js

$(function(){

    $('#search').keyup(function(){
        $.ajax({
            type: "POST",
            url: "/articles/search",
            data: {
                'search_text' : $('#search').val(),
                'csrfmiddlewaretoken' : $("input[name=csrfmiddlewaretoken]").val()
            },
            success: SearchSuccess,
            dataType: 'html'
        });
    });
});

function searchSucces(data, textStatus, jqXHR){
    $('#search-results').html(data);
}

I'm a beginner at Django, and this form come from this tutorial. Thank you for your time.